1. Field of the Invention
The present invention relates to apparatus for distilling water to remove contaminants and, more particularly, relates to a highly efficient water distiller suitable for home or office use.
2. Description of the Background
Water distillers have been used for decades to purify water. Water distillation provides an effective and highly efficient technique for removing bacteria, chemicals, and toxic organic compounds from contaminated water. In recent years, the public has become more aware of the fact that regular water supplies, including "tap" water supplied by a municipality and local or regional well water, often contains dissolved gases, e.g., sulfur dioxide, and/or other contaminants which are harmful to health. The distillation process heats the water to produce steam, and then condenses the steam to form water free from such contaminants. The contaminants having a vaporization temperature higher than that of water remain in the heating unit of the distiller, while solvents which have a boiling point lower than water may be separated from the steam by venting prior to condensation.
U.S. Pat. No. 771,832 discloses a crude water distiller with a bunsen burner for heating the water. U.S. Pat. No. 3,445,344 discloses a complex distiller with a pump having a rotating inverted open cone. U.S. Pat. No. 3,489,649 discloses a distiller with two separate boiling chambers for achieving double distillation.
U.S. Pat. No. 3,660,246 discloses a distiller with a vertical riser between a distillation chamber and a condensation chamber. The distillate enters an expansion zone and exits through perforations, where it is cooled by a spiral cooling coil. U.S. Pat. No. 3,907,683 discloses a distiller with a constant head reflux condenser to closely regulate the temperature and flow rate of the water from the condenser to the evaporator. U.S. Pat. No. 4,110,170 discloses a condenser which controls the entry of water to the distiller by sensing the temperature of the distillate.
U.S. Pat. No. 3,838,016 teaches a distiller which utilizes spiral condenser coils. A first float is responsive to the water level in the heating unit, and a second float is responsive to the water level in the condensing unit. Each float operates a microswitch, and the signals from each of the floats operates the distiller. U.S. Pat. No. 4,331,514 discloses a distiller with a float valve which regulates the level of water in a boiling chamber. U.S. Pat. No. 4,339,307 discloses a distiller with separate float valves for controlling the water level in a preheat unit and the boiler unit.
An improved water distiller is disclosed in U.S. Pat. No. 4,724,048. This water distiller includes a substantially vertical chimney for passing steam from the heating unit to the condensing unit, and a inner tube axially positioned within the chimney for passing preheated water to the heating unit. In one embodiment, the distiller includes an air-cooled condenser with a blower for removing heat from the condensing steam.
In spite of all the attempts to devise an improved distiller, prior art distillers for home use nevertheless have significant disadvantages which have limited their acceptance. The distillers have generally been considered too costly to operate, since a relatively high wattage is required to produce purified water. Although prior art distiller units advertise that eleven gallons of distilled water per 24 hours is available from a unit operating at 1200 watts, this efficiency is difficult to obtain and more difficult to maintain. Moreover, many lesser priced units cannot even achieve this efficiency.
A further disadvantage of prior art distillers relates to the difficulty with cleaning distillers having floats for sensing water levels and thereby regulating the flow of water to the distiller. Such floats are subject to collecting scale and other debris, and do not maintain the water level in the heating unit of the distiller at a constant value.
The disadvantages of the prior art are overcome by the present invention, and an improved home distiller is hereinafter disclosed which has a high efficiency compared to prior art distillers for producing distilled water.